I am facing a problem in first and 2nd gear in my VW Polo diesel car. I am unable to move car in these gears, I tried it so many times. So for the time being I used 3rd gear to move the car & after that 4th, 5th continue working, but when I reached home after 5-6 kms, there I found some smell of burning thing. I think it's clutch plates' outer edge or another thing. I have no indication & markup in the speedometer screen. What is the cause? Does it damage clutch plates?
If you are able to physically select first or second gear then it is likely that your clutch is worn to excess. You may also find that flooring the gas pedal when moving causes the engine note and revs to rise without any appreciable increase in speed.
Depending on the year of your car, it may be that the hydraulic actuator for the clutch is simply low on fluid but it does sound more likely that your car needs a new clutch pack.
I am guessing that you can't select 1st and 2nd because the gear selector linkages are worn. I doubt it is the clutch slipping because you would find it difficult to pull away in 3rd with a slipping clutch.
The smell is probably due to you riding the clutch so much trying to pull away in 3rd. If the clutch isn't already slipping, it probably will be soon if you keep doing this.
There is plenty of info on the internet, including on youtube about replacing worn selector linkages.